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A new study of rock samples collected during the Apollo missions has concluded the Moon is almost bone dry.

The research published today in Science Express means the only water on the Moon was most likely deposited by comet or asteroid impact.

The finding may also have implications for theories regarding the origins of water on Earth.

To reach their conclusion a team of scientists led by Dr Zachary Sharp from the University of New Mexico looked at chlorine isotopes in lunar volcanic rocks.

Chlorine is hydrophilic - attracted to water - making it an extremely sensitive indicator of hydrogen levels.

If the Moon contained a similar amount of water as the Earth, than the ratio of chlorine isotopes in the rocks would also be similar to those found on here. Instead, the researchers found the range of chlorine isotopes contained in the lunar samples to be 25 times greater than what is found in rocks and minerals from Earth and from meteorites.

Sharp and colleagues conclude the interior of the Moon is anhydrous - contains no water.

Scientists still believe the discovery of water molecules at the bottom of craters in the Moon's polar regions indicate an abundant supply of water in these regions, which could be used by future lunar colonies for drinking, oxygen and rocket fuel production.